Question

If the volume of this pyramid is 80 cm3, what is its height?
http://i1052.photobucket.com/albums/s441/leya454/VHS_GMT_08_18_UT_ques12.gif
2.7 cm

4 cm

8 cm

13 cm

Answer 1

Vol of Pyramid = 1/3 x [Base Area] x height
But Base Area = 1/2 x base x height (formula for triangle)
Base Area = 1/2 x 12 x 5 = 30
=> Vol of Pyramid = 1/3 x 30 x height
Vol of Pyramid = 10 x height
But Vol of Pyramid = 80cm^3
=> 80 = 10 x height
(Divide both sides by 10)
Therefor height = 8cm

Answer 2

thank you!